% 

function [w, ex, ey,bb_spd] = D2Q9_lattice_parameters()

w = [4/9, 1/9, 1/9, 1/9, 1/9, 1/36, 1/36, 1/36, 1/36];
ex = [0, 1, 0, -1, 0, 1, -1, -1, 1];
ey = [0, 0, 1, 0, -1, 1, 1, -1, -1];
bb_spd = [1, 4, 5, 2, 3, 8, 9, 6, 7];